Throughout this application, various publications, patents and published patent applications may be referred to by an identifying citation. The disclosures of the publications, patents and published patent applications referenced in this application are hereby incorporated by reference into the present disclosure.
Microfabrication techniques, such as photolithography commonly used in the microelectronics industry to produce microprocessors and memory chips, have been increasingly used to fabricate other types of products, such as MEMS (Micro Electro-Mechanical Systems) devices and the like. These techniques advantageously enable the production of increasingly miniaturized devices, for use in products of ever decreasing size.
Those skilled in the art will recognize that these microfabrication techniques are particularly well suited to the production of relatively small, monolithic, two-dimensional (2-D) devices, due to their precise, deposited-layer fabrication approach. However, the inherent two-dimensionality of microlithography, in combination with the limited depth of vision associated with the small wavelengths necessitated by its micrometer precision capability, tends to militate against its use for relatively large (meso-scale) 3-D assemblies. This phenomenon thus effectively precludes the production of devices having larger aspect ratios, and/or larger out-of-plane dimensions. This microfabrication approach also tends to be ill-suited for larger, meso-scale devices in general, due to the increasing complexity associated with designing 3-D features for nominally microlithographic 2-D fabrication. In addition, as these devices become larger and more complex, there tends to be greater opportunity for generally incompatible process steps and/or parasitic errors, etc.
One attempt to address these concerns includes the microfabrication of discrete components, which are subsequently fastened to one another. This approach provides for the possibility of effectively isolating incompatible process steps to separate components, while also enabling the fabrication of larger, 3-D assemblies. Disadvantageously, however, it tends to be difficult to join these discrete components with the same level of precision (e.g., micrometer level), to which the components themselves are fabricated. As such, the components are either joined with less precision, which may defeat the purpose of using such a precise fabrication approach in the first place, or substantial costs may be incurred through the use of high precision assembly systems.
Micro-machined clips have been used to align and hold optical fibers, to position structures perpendicular to the substrate and as general purpose in-plane fasteners. LEGO-like systems to align and bond wafers for packaging have been proposed. Others have proposed micro-mechanical Velcro to mechanically bind wafers, without providing for relative positioning of the wafers. However, these approaches tend to either require complex assembly equipment, or result in relatively high assembled misalignments. (See, e.g., Bostock, et al., “Silicon Nitride Microclips for the Kinematic Location of Optic Fibers in Silicon V-Shaped Grooves”, Journal of Micromechanics and Microengineering, Vol. 8, 1998, pp. 343-360. Last, et al., “Out of Plane Motion of Assembled Microstructures using a Single-Mask SOI Process,” Proc. 13th International Conference on Solid-State Sensors, Actuators and Microsystems, IEEE, New-York, June 2005. Prasad, et al., “Design, Fabrication, and Characterization of SCS Latching Snap Fasteners for Micro Assembly,” Proc. ASME International Mechanical Engineering Congress and Exposition (IMECE), ASME, New-York, November 1995. Lee, et al., “A Morphology-Independent Wafer Level Rivet Packaging with Lego-Like Assembly,” Proc. 13th International Conference on Solid-State Sensors, Actuators and Microsystems, IEEE, New-York, June 2005. Han, et al., “Micromechanical Velcro,” Journal of MicroElectroMechanical Systems, Vol. 1, No. 1, March 1992.)
A need, however, exists for an assembly approach and system capable of enabling discrete, high-precision microfabricated components to be easily hand-assembled without substantial loss of precision.